Two-way ground burrowing device



Oct. 29, 1968 K. ZYGMUNT ET 3,407,334

TWO-WAY GROUND BURROWING DEVICE 5 Sheets-Sheet 2 Oct. 29, 1968 FilgdApril 11. 1967 FIG. 4

K. ZYGMUNT ET AL TWO-WAY GROUND BURROWING DEVICE INVENTORS KAZIMIERZ ZYGMUNT TADEUSZ GERLACH ATTORNEYS Oct. 29, 1968 Filed April 11, 1967 FIG. 6

. K. ZYGMUNT ET AL TWO-WAY GROUND BURROWING DEVICE 5 Sheets-She et 5INVENTORS KAZIMIERZ zveuum' mpzusz GERLACH Y fihmwj a ML ATTORN EYSUnited States Patent O" ABSTRACT OF THE DISCLOSURE A pneumaticallydriven ground burrowingdevice having a driving ram contained therein andoppositely facing anvil walls at the opposite ends of the ram, and apneumatically operated control mechanism for driving the ram in a'working stroke toward either of the anvil walls to selectively drive thedevice in a forward burrowing direction through the ground or a rearwardretracting direction through the burrowed hole.

Cross-reference to related application This application is acontinuation-in-part of our copending application, Ser. No. 414,054filed Nov. 25, 1963, now abandoned and entitled Self-Moving PneumatiHammer for Ground Burrowing.

BACKGROUND OF INVENTION Field of the invention The present inventionpertains to devices for burrowing holes in the ground and moreparticular to a pneumatically operated ground burrowing device capableof being driven under power in both a'forward burrowing direction and arearward retracting direction with the driving mechanism for producingsuch movement being contained wholly within the device and actuated bycompressed air fed from a source outside the burrowed hole.

Description of the prior art Ground burrowing devices to which thepresent invention relates have been constructed for two-way poweroperation. This two-way power operation is advantageous in that the samepneumatic pressure source used in driving the device in a forwardburrowing direction may also be used in power driving the device in aretracting direction. In burrowing a horizontal hole through the ground,for example, it is sometimes not convenient to remove the device throughthe forward end of the hole when the burrowing operation has beencompleted. Also, in burrowing'a hole, an immovable object mayoccasionally be encountered and require rearward removal of the devicefrom the burrowed hole. Devices constructed to operate under power inboth a forward and rearward direction are disclosed, for example, in US.Patent No. 3,137,483 granted June 16, 1964. In such devices two chambersare formed internally of the device by the internally disposed hammeringram and these chambers are provided with separate outlet passageways foreffecting forward 'and rearward motion, with the reversingbf themotionrequiring the closing of one of the passageways and the opening of theother. With this construction; the necessary, crosssectional size of thepassageways is quite large and this renders it difficult and expensiveto construct a workable device. Besides the difficulties encountered inproviding 3,407,884 Patented Oct. 29, I9 68 ice room for the twopassageway systems inside the device while still maintaining theoverallouter dimension within reasonable limits, difficulties with the normaloperation of the device are sometimes encountered due to thenecessity ofconnecting the closed passageways, capable of receiving a largepneumatic flow, with the interior of'the cylinder. SUMMARY OF THEINVENTION In accordance with the teachings of the presentinvention, aself-moving ground burrowing; device havingan improved construction foreffecting forward and rearward motion and having an improved efiiciencyis provided. The ground burrowing device generally includes an outerca'sing, a separate inner cylinder and a piston ram slidably disposedwithin the inner cylinder for movement in a driving stroke toward eithera front anvil wall located at the front end of the cylinder or toward aback anvil wall located at the rear of the device. In addition a hose isprovided for supplying pneumatic pressure such as compressed air to theinterior of the device through the rearward end thereof, and aninternally contained valve mechanism is provided for changing thedirection of flow of the compressed air through the interior of thedevice to effect either a forward driving movement through the ground ora retracting movement through the burrowed hole. The inner cylinder andram member of the device divide the interior thereof into threechambers, namely a front chamber which is kept in continualcommunication with the source of compressed air through a conduitextending through the ram to continually urge the ram with apredetermined force in a rearward direction; a middle chambersurrounding the ram intermediate its ends and which is kept in continualcommunication with the atmosphere through an exhaust passageway; and arear chamber dis posed rearwardly of the ram and which is selectivelyconnectable in a prescribed manner to the source of compressed air fordriving the device in a forward direction and to atmosphere for drivingthe device in a rearward retracting direction.

With applicants construction, the overall cross-sectional dimension ofthe device may be made small since the passageway supplying compressedair to the front chamber extends through the ram rather than through theouter casing structure; and since the control mechanism for changing thedirection of movement of the device is wholly contained and operable inthe rear of the device while the front chamber remains in communicationwith the source of compressed air, the construction of the device isgreatly simplified. Furthermore, by containing the ram within a separatecylinder disposed internally of the .device, the outer casing of thedevice may be subjected to external deforming forces as it is movedthrough the ground without causing deformation of the inner cylinderwith resulting binding of the ram and failure of the device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectionalview of one embodiment of the present invention;

FIG. 2 is an enlarged sectional view showing the reversing mechanism ofthe embodiment of the invention shown in FIG. 1 in position foreifecting forward movement of the device; FIG. 3 is an enlargedsectional view similar to FIG. 2

and showing the reversing mechanism in position for effecting a rearwardmovement of the device;

FIG. 4 is a longitudinal sectional view of a modified embodiment of thepresent invention;

FIG. 5 is an enlarged sectional view showing the reversing mechanism ofthe embodiment of the invention shown in FIG. 4;

FIG. 6 is an enlarged sectional view showing the reversing mechanism ofstill another embodiment of the present invention; and

FIG. 7 is an expanded view of the guide track of the reversing mechanismshown in FIG. 6.

Description. of the preferred embodiments With reference to FIG. 1, theembodiment of the ground burrowing device there shown comprises an outercasing 1 which includes a front projectile shaped nose member 2,intermediate cylindrical member 3 and a rear terminal end member 4. Inthe nose of the device, there is located a chisel member 5, or othersuitable cutting implement, the back end of which forms a front anvilwall 6 for a ram member 7. The ram member is located internally of theouter casing 1 and has a reduced front section 8 and an enlarged rearsection 9 slidably disposed within an inner cylinder member 10. Thecylinder 10, is, in turn, constructed with a front section 11 sealinglyengaging and supporting the front section of the ram and an enlargedrear section 12 sealingly engaging and supporting the rear section ofthe ram. The cylinder is fixed to the outer casing by threading thecylindrical member 3 thereof onto the nose member 2 and the cylinder 10is held resiliently in place by the flexible elastic elements 13 whichmay be made of rubber or similar material.

The ram and inner cylinder of the device divided its interior into threeseparate chambers spaced axially therealong. These chambers are thefront chamber. 14, the middle chamber 15 and the rear chamber 16.

The front chamber 14 surrounds the front end of the ram and iscontinually maintained in communication with the source of compressedair used in operating the device. For this purpose, the ram is providedwith an axially extending conduit 17. The forward end of this conduitextends through the forward end of the ram; and in addition, radialbores 18 are provided in the forward end of the ram so that the chamber14 will remain in communication with the conduit 17 when the ram is inabutment against the anvil wall 6. To the rear of the ram a cylindricalduct 19 is connected and this duct leads to a flexible hose 20 connectedto the rear end of the device.

The middle chamber 15 surrounds the ram intermediate its ends and iscontinuously maintained in communication with the atmosphere by exhaustports 21 in the wall of the cylinder 10 leading to an exhaust passageway22. The passageway 22 is formed by the radial spacing between theenlarged rear section 12 of the cylinder and the intermediatecylindrical member 3 of the outer casing and extends through theterminal end member 4 at the rear end of the device.

The rear chamber 16 is defined by the spacing between the enlarged rearsection 12 of the cylinder 10 and the cylindrical duct 19. This chamberis bounded at its axial ends by the rear end 23 of the ram and by theforwardly facing wall 24 of a buffer member 25 located at the rear endof the cylinder 10. The wall 24 defines the rear anvil wall of thedevice as more fully described below. The rear chamber 16 has two setsof ports 26 and 27 leading to the exhaust passageway 22. The ports 26functionas primary ports and are located near the forward end of therear chamber and the ports 27 function as auxiliary ports and arelocated near the rearward end of this chamber.

The control valve structure for operating the device in both a forwardand rearward direction is shown at 28. This valve includes a casing 29connected to the bulfer member 25 in the rear of the cylinder 10 by nuts30, 31

and rubber shock absorbers 32. Inside the casing 29 there is a valvebody member 33. Extending through the body member there are amultiplicity of air ducts 34. These air ducts at their forward endcommunicate with the rear chamber 16 via the air inlet passageway 35provided by the spacing between the duct 19 and the casing 29. The rearend of these ducts 34 open into an annular chamber 36 which is connectedvia a plurality of radial openings 37 with the source of compressed airentering the rear of the device through the hose 20. The valve 28further includes a valve ring plate 38 and a valve spring 39. The plate38 is adapted to move between a closed position engaging the body member'33 and closing the air ducts 34 and an open position spaced from thebody member to effect repeated actuation of the device in either aforward or rearward direction as more fully described below.

Positioned rearwardly of the valve mechanism 28 is the starting valve 40of the device. The starting valve includes an outer body member 41connected within the rear of the casing 29 and a slider valve member 42slidably disposed within the outer body member 41. A spring 43 normallyurges the slider valve 42 forwardly of the device into a positionclosing the opening 37 to the chamber 36. The spring 43 is positionedwithin a chamber 44 formed between the slider valve 42 and the outerbody member 41; and depending on the position of the valve 42, thischamber is adapted to connect with either the atmosphere through theports 45 and grooving 46 or with the source of compressed air throughthe ports 47. The starting valve is supported within the device by meansof wing shaped consoles of the terminal member 48 which also serve tofix the hose 20 for the compressed air supply.

For controlling the direction of movement of the device a servomotorcomprising a reversing valve 49 is provided. This reversing valveincludes a cylinder member 50 slidably mounted on the casing 29 of thecontrol valve 28. The rearward end of the cylinder 50 is connected bymeans of rear ports 51 with the chamber 36 and the forward end thereofto the exhaust passageway by means of the forward ports 52. These ports51 and 52 also connect to a common chamber 53 in which a valve plate 54and spring 55 are contained. The reversing valve also includes a slidermember 56 slidably received over the rear section of the cylinder 10.The slider member 56 is connected to the cylinder member 50 by means oftwo screws 57, only one of which is shown in the drawings, and theelastic bushes 58. The reversing valve is urged rearwardly of the deviceby means of a spring member 59.

The reversing valve functions to effect an opening and closing of theauxiliary ports 27 in the cylinder 10 connecting the rear chamber 16 tothe exhaust passageway 22. FIG. 2 shows the position of the reversingvalve when the device is to be driven in a forward direction. As thereindicated, the auxiliary ports 27 are closed by the slider member 56.FIG. 3, on the other hand, shows the reversing valve in a retractedposition opening the auxiliary ports 27. In this position, the devicewill be driven in a rearward direction. In both FIGS. 2 and 3, the partsof the device are shown under operating conditions with compressed airbeing supplied through the hose 20 to the interior chamber and valves.

The operation of the embodiment of the invention shown in FIGS. l-3 isas follows: First, assuming that no compressed air has yet been suppliedto the device, the starting valve 40 will, due to the action of thespring 43, be in a forward position closing the openings 37 while theslider member 56 of the reversing valve will be in its rearward positiondue to the action of the spring 59. Also, the valve plate 54 of thereversing valve and'the valve plate 38 of the control valve will be intheir rearward positions due to the action of the springs 55 and 39.Accordingly, the ports 51 of the reversing valve will be closed and theair ducts 34 of the control'valve will be open.

When starting the device for forward movement, compressed air issupplied through the hose 20. The compressed air flows from the hosethrough the starting valve slider 42, the duct 19, the axial conduit 17and radial bores 18 of the ram 7 and into the forward chamber 14. Thecompressed air also flows through the ports 47 in the starting valveslider member and into the chamber 44 to keep the starting valve in itsforward position. The starting valve will remain in this forwardposition until the pressure of the compressed air reaches apredetermined value and the force of the air acting against the forwardsurfaces 60, 61 thereof is suflicient to overcome the spring 43 and theforce of the air acting against the rearward surface 62 of the slider42. Since it takes a period of time for the pressure to build up in theinterior of the device, the starting valve will not immediately move toits retracted position. Accordingly, the chamber 36 will not receive anycompressed air and thus the compressed air will be prevented fromentering the rear chamber 16 via the air ducts 34 and the air inletpassageway 35.

As the pressure within the front chamber increases, the ram will becaused to move in a rearward direction and since the auxiliary ports 27of the rear chamber are open, there will be no resistance to therearward movement until the ram passes over these ports. At this time,the slider valve 42 will be caused to move rearwardly and the chamber 44will become connected to atmosphere through the grooves 46 and ports 45.Once the starting valve has been moved rearwardly, it will remain thereduring the entire working time of the device; and once it is moved tothis retracted position, compressed air will enter the chamber 36, passthrough the ports 51 and act against the valve plate 54 of the reversingvalve. In forward operation, the pressure of the compressed air suppliedto the device will be high enough so that the air acting against thevalve plate 54 will be sufficient to overcome the force of the spring 55to close the ports 52 and open the ports 51 to the chamber 53. Thus thechamber 53 will be supplied with compressed air through the ports 51.For forward operation, the pressure of the compressed air supplied tothe chamber 53 will be sufficient to compress the spring 59 and move thereversing valve into the forward position shown in FIG. 2 to close theauxiliary ports 27 leading to the rear chamber 16.

As the compressed air enters the chamber 36, it will also pass throughthe open ducts 34 of the control valve and supply full pressure to therear chamber 16; and Since the auxiliary ports 27 are held closed by theslider member 56 of the reversing valve and since the diameter of therear end of the ram 7 is greater than the diameter of its front end, theram will be driven forward and impact againstthe front anvil wall 6causing the device to move through the ground. In the final phase ofthis motion, just before the ram strikes the anvil wall 6, the primaryopenings 26 in the rear chamber will be opened. Accordingly, thepressure in the rear chamber will drop to atmosphere and thus thecompressed air within the chamber 36 will cause a closing of the valveplate 38 of the control valve. For effecting this result, the spring 39is chosen so that by itself it is not capable of overcoming the pressurein the chamber 36 to hold the valve plate 38 open. Instead, it takes theforce of this spring plus the force of the compressed air from thechamber 16 acting through the air ducts 34 to hold this valve plate openwhen the chamber 36 is supplied with compressed air.

After the impact of the ram 7 against the anvil wall 6 of the chisel 5,with the resulting opening of the primary ports 26, the compressed airin the front chamber 14 acts on the ram to move it rearwardly. After theprimary openings 26 are closed by the movement of the ram, the airtrapped within the rear chamber is gradually compressed. As the ramnears its rearwardmost position, this compression of the air in the rearchamber becomes sufficiently great to overcome the pressure of thecompressed air in the chamber 36; and therefore, the valve plate 38 willbe moved to its open position. The size of the ram 7 and cylinder 10 aresuch that the ram 7 in moving rearwardly elfects an opening of thecontrol valve before the ram reaches the rear anvil wall 24. With theopening of the control valve, the chamber 16 is once again supplied withfull pressure of the compressed air,and the ram 7 is once again drivenforwardly against the anvil wall 6.

When it is desired to withdraw the burrowing device through the burrowedhole, this is simply effected by momentarily shutting off the supply ofcompressed air and restarting the device at a suitably lower pressure,that is, at a pressure which is low enough so that the air in thechamber 36 acting against the valve plate 54 of the reversing valve isnot sufficient to overcome the spring 55. Thus the ports 51 remainclosed and the slider member 56 remains in its rearward position leavingthe auxiliary ports 27 of the rear chamber 16 uncovered. Accordingly, asthe ram begins its forward movement toward the front anvil wall 6, theauxiliary ports will be opened and produce a pressure drop in the rearchamber 16. With this pressure drop, the compressed air within thechamber 36 of the control valve will cause the valve plate 38 to moveagainst the action of the spring 39 and close the air ducts 34. Furthermovement of the ram forwardly will therefore be due to the kineticenergy and this movement will be decelerated by the pressure of thecompressed air in the front chamber 14.

The position of the auxiliary ports. is so determined that the ram isstopped before impact with the front anvil wall 6 and the pressurewithin the front chamber then drives the ram re'arwardly against therear anvil wall 24. -In the final phase of the rear motion of the ram 7,it covers the auxiliary holes 27 and compresses the air contained withinthe rear chamber 16. This causes the valve plate 38 of the control valveto open and the compressed air entering the chamber 16 again moves theram toward the front of the device to repeat the cycle just described.

The forward motion of the device as well as the rearward motion is onlypossible when the frictional forces between the outer casing of thedevice and the ground are suflicient to balance the recoil. The joiningof the outer casing of the device with the inner cylinder 10 by means ofthe elastic elements 13 renders it possible, however, to use inexpensivegrades of steel for the cylinder 10 since any deforming forces exertedon the outer casing are not transferred to this cylinder. Also, with thevalving and chamber structure of the device shown in FIGS. 1-3, thefront chamber 14 need not be vented to atmosphere to elfect a' forwardworking stroke of the ram 7 or to effect a cocking of the ram at theforward end of the device preparatory to a rear ward stroke.Accordingly, the outer casing does not require any conduits leading tothe front chamber 14 and thus the cross-sectional size of the device maybe kept to a minimum and its overall construction greatly simplified.

In the embodiment of the present invention shown in FIGS. 4 and 5,primed reference numbers are used for designating the parts which aresimilar to the parts of the device shown in FIGS. 1-3.

In the device shown in FIGS. 4 and 5, the ram 7' is a two part structureand is guided in an inner one part cylinder 10'. The cylinder 10 isconnected to the outer casing 1 between the nose member 2 and thecylindrical member 3' by the threaded joints at the forward end of thecylinder. As with the construction shown in FIGS. 1-3, the ram 7' has areduced ront section 8' and an enlarged rear section 9; and the cylinder10' is constructed with a reduced front section 11' and an enlarged rearsection 12' sealing, engaging and supporting the ram.

The movement of the ram 7' inside the cylinder 10' is limited in itsforward stroke by the anvil wall 6' and in its rearward stroke by therear face 23 of the boss contacting the front part of the cylinder 10fwhich de- 7 fines the rear anvil wall 24 of the device. With thisconstruction, the mounting of a separate rear buffer is avoided and theplacing of the control valve 28' and the reversing valve 49 immediatelyin the rear of the rear section 12' of the inner cylinder is renderedpossible.

As in the embodiment of the invention shown in FIGS. 13, the ram 7' andinner cylinder 10 divide the interior of the device into a front chamber14, a middle Chamber 15' and a rear chamber 16'; and these chambers areconnected to exhaust and compressed air in the same manner as with theconstruction of FIGS. 1-3. However, instead of using a slider member forcontrolling the opening and closing of the auxiliary ports 27' in therear chamber 16, these ports are covered and opened by a modifiedreversing valve structure 49".

As shown in FIGS. 4 and 5, the reversing valve in cludes an elastic ringvalve 63 positioned in overlying relationship with the auxiliary ports27. The valve 63 is placed in a basket member 64 which is held fixedagainst the rear end of the cylindrical member 3 of the outer casing ofthe'device by the terminal end member 4'. The terminal end member 4'also connects a shock absorber assembly 65 to the rear end of thedevice; and to this shock absorber assembly the outer body member 41' ofthe starting valve is connected by means of the elastic members 66.

The valve 63 operates to close and open the auxiliary ports .27 by beinginflated and deflated. For this purpose, the rear end of the valve 63 isconnected via the thin conduit or hose 67 with the source of compressedair. The forward motion of the device is thus effected by filling thevalve with compressed air to cause it to inflate and close the auxiliaryports 27. Conversely, rearward motion of the device is produced bylowering the pressure inside the valve 63 to cause it to deflate andopen the auxiliary ports.

In the embodiment of the device shown in FIGS. 4 and 5, the constructionand operation of the control valve 28 and the starting valve 40' is thesame as in the device of FIGS. 1-3. Similarly, the movement of the ram7' is also the same as in the device shown in FIGS. 1-3. However, withthe device shown in FIGS. 4 and 5, the reversing of its direction ofmovement through the ground does not require the reduced pressurenecessary with the device of FIGS. 1-3 for effecting a rearward motion.This is advantageous under conditions where for some reason the devicehas become wedged in the burrowed hole or a rock or dirt has fallen downbehind the device and a greater force is required to effect removal ofthe device from the burrowed hole.

FIGS. 6 and 7 show a third embodiment of the present invention which,like those shown in FIGS. 15, is const-ructed to operate in both theforward burrowing direction and the rearward retracting direction. Withthe exception of the reversing valve, the device of FIGS. 6 and 7 issubstantially identical to that shown in FIGS. l-3. Accordingly, likereference numerals with a double prime have been used to designate likeparts in FIG. 6 and for a description of these parts, reference is madeto the description of the device of FIGS. l3.

The reversing valve 49" of the construction shown in FIGS. -6 and 7differs from that shown in FIGS. 13 in that its movement back and forthbetween a forward position closing the auxiliary ports 27" of the rearchamber 16" and a rearward position exposing these ports is notdependent on different pressures of the compressed air supplied to thedevice. Instead, movement between the forward and rearward positions isproduced by momentarily shutting off the supply of compressed air. Thatis, each time the supply of compressed air is shut off and thenre-established, the reversing valve will automatically shift from oneposition to the other. As shown in FIGS. 6 and 7, the reversing valvecylinder member is slidably received over the casing 29" of the controlvalve 28". The axial space between the two members 50" and 29 defines achamber 53" which is connected to the chamber 36" via the ports 51" andthus, to the source of compressed air via the openings 37". It is to benoted that no ports similar to the ports 52 of the device of FIGS. 13are provided for connecting the chamber 53" to exhaust and that instead,the chambers 53" and 36" are maintained in continuous communication witheach other.

On the interior wall of the cylinder 50", a circumferential groove 68 isprovided. In this groove a ball race member 69 is secured; and on thesurface of the race facing the casing 29" a circular ball track 70 isformed for receiving a ball member 71 of the reversing valve. Theposition of the ball member 71 controls the position of the reversingvalve; and for this purpose, the outer surface of the casing 29" isprovided with a grooved guide track 72 in which the ball rests.

In the operation of the reversing valve, the spring 59" continuouslyurges the slider member 56" and the cylinder member 50 with the ball 71to the rear of the device, this direction being represented in FIG. 7 bythe arrow A. When the device is connected to the source of compressedair, however, the force of the spring 59" is overcome and the reversingvalve with the ball member thereof is urged forwardly or in thedirection of the arrow B shown in FIG. 7. Each time the source ofcompressed air to the device is shut off, the spring will take over thecontrol of the reversing valve and move it rearwardly to open theauxiliary ports 27"; and each time the source of compressed air isre-established, the reversing valve will be caused to move forwardly andthe extent of this forward movement will be determined by the particularposition of the ball within the track.

As shown in FIG. 7, the guide track includes a first branch section 73extending obliquely through a first predetermined distance toward thefront of the device, a second branch section 74 connected to the firstbranch section at a point rearwardly of its forward end and extendingobliquely toward the rear of the device, a third branch section 75connected to the second branch section at a point forwardly of itsrearward end and extending obliquely through a second predetermineddistance less than the first predetermined distance toward the front ofthe device, a fourth branch section 76 connected to the third branchsection at a point rearwardly of its forward end and extending obliquelytoward the rear of the device and connecting to another first branchsection 73 at a point forwardly of its rearward end. This arrangement ofthe branch sections 73-75 is repeated to form a continuous track aroundthe outer surface of the casing 29".

Also, as shown in FIG. 7, each of the branch sections 73 and 74 of thetrack are connected together in the manner described above by theaxially extending sections 77. These sections receive the ball 71 as itis moved forwardly of the device under the influence of compressed airand thus lengthens the axial movement of the slider member 56" of thereversing valve.

With the above-described construction of the guide track, the ball, asit is moved forwardly and rearwardly with the cylinder member 50" of thereversing valve will also move around the casing 29" of the controlvalve in the direction indicated by the broken arrows. FIG. 7 shows oneposition of the ball as would occur with compressed air being suppliedto the device. As there indicated, the ball is received in one of theaxial branches 77. Thus, the slider member 56 of the reversing valvewill be in its forwardmost position overlying the auxiliary ports 27" asshown in FIG. 6, the forward extent of this movement being limited byengagement of the reversing valve with the rear end of the buffer member25".

When it is desired to reverse the direction of movement of the device,the compressed air is shut off. The spring 59 then takes control andmoves the reversing valve with the ball 71 rearwardly; and due to theconnection of the branch section 74 with the section 73 at a pointrearwardly of the forward end of the section 73, the ball will be causedto move into the section 74 and to its rearward end. When the compressedair is resupplied to the device, the reversing valve with the ball willbe forced forwardly of the device; and due to the connection of thebranch section 75 with the section 74 at a point forwardly of itsrearward end, the ball will be caused to move into the section 75 and toits forward end. This will stop the forward movement of the reversingvalve at a location rearwardly of the auxiliary ports and thus theseports will remain uncovered and the device will operate in a retractingdirection.

From the above, it will be evident that each time the compressed air isshut off and reconnected, the ball will be caused to move through thenext branch sections of the guide track to alternately open and closethe auxiliary ports 27". The extent of axial movement of the reversingvalve between its opened and closed positions is the distance betweenthe forward end of the branch sections 75 and the forward end of theaxial branch sections 77. This is represented in both FIGS. 6 and 7 atX.

In the description of the present invention as given above, referencehas been made to three particular embodiments; however, it is to beunderstood that various changes may be made thereto without departingfrom the scope of the invention as set forth in the following claims.

What is claimed is:

1. A two-way ground burrowing device comprising:

(a) an elongated outer casing having a tapered forward end and a hollowinterior;

(b) a ram disposed within the interior of said casing for axial movementtherealong, said ram having a front section of reduced cross-sectionaldimension and a rear section of enlarged cross-sectional dimensron;

(c) first supporting means for slidably and sealingly supporting thefront section of said ram about its outer periphery;

(d) second supporting means for slidably and sealingly supporting therear section of said ram about its outer periphery;

(e) a first chamber disposed within the interior of said casing andcommunicating with the front end of said ram;

(f) a second chamber disposed within the interior of said casing andcommunicating with the intermediate portion of the piston where thefront and rear sections join each other, said second chamber beingisolated from said first chamber;

(g) a third chamber disposed within the interior of said casing andcommunicating with the rear end of said ram, said third chamber beingisolated from said second chamber and having one wall thereof defined bysaid second supporting means;

(h) a front anvil wall positioned within the interior of said casing inthe path of forward movement of said ram; I

(i) a rear anvil wall positioned within the interior of said casing inthe path of rearward movement of said ram;

(j) a compressed air inlet at the rear end of the interior of saidcasing adapted to be connected to an extraneous source of compressedair;

(It) conduit means for continuously maintaining said first chamber incommunication with said compressed air inlet for continuously urgingsaid ram in a rearward direction;

(l) first port means for continuously maintaining said second chamber incommunication with the exterior of said casing;

(m) second port means in the second supporting means for connecting theforward end of said third chamber to the exterior of said casing, saidsecond port means being located immediately rearwardly of the rear endof said ram When said ram is in its forwardmost position abutting saidfront anvil wall and adapted to be closed from communication with saidthird chamber by the rear section of said ram when said ram is spacedrearwardly of said front anvil wall;

(n) third port means for connecting the rearward end of said thirdchamber to the exterior of said casing, said third port means beinglocated in said second supporting means whereby it is closed by the rearsection of said ram immediately before said ram reaches its rearwardmostposition abutting said rear anvil wall;

(0) first valve means for selectively maintaining said third port meansopened or closed independently of the opening and closing thereof bysaid ram; and

(p) second valve means for connecting and disconnecting said thirdchamber to said source of compressed air, said valve means beingresponsive to changes in pressure in said third chamber and being openedby increased pressure in said third chamber.

2. A two-way ground burrowing device according to claim 1 wherein saidconduit means for continuously maintaining said first chamber incommunication with said compressed air inlet comprises:

(a) an axial bore extending through said ram; and

(b) a cylindrical duct positioned within the interior of said casing andhaving one end slidably and sealingly received within the axial bore ofsaid rarn at the rear thereof and its other end connected to saidcompressed air inlet.

3. A two-way ground burrowing device according to claim 2 wherein:

(a) said first and second supporting means are defined by inner cylindermeans connected to said outer casing and having a front section ofreduced cross-sectional dimension supporting the front section of saidram and a rear section of enlarged cross-sectional dimension supportingsaid rear section of said ram.

4. A two-way ground burrowing device according to claim 3 wherein:

(a) said rear anvil wall is defined by the front end of said innercylinder means; and

(b) said ram includes a radially outwardly extending boss adjacent itsforward end having a rearwardly facing surface axially aligned with saidrear anvil wall for abutting thereagainst when said ram is in itsrearwardmost position.

5. A two-way ground burrowing device according to claim 4 wherein saidfirst valve means for selectively maintaining said third port meansopened or closed independently of the opening and closing of said ramcompr1ses:

(a) an inflatable, elastic ring valve surrounding the rear section ofsaid inner cylinder means in overlying sealing relationship with saidthird port means when inflated, and in spaced relationship therewithwhen deflated; and

(b) means for selectively connecting said ring valve to said source ofcompressed air.

6. A two-way ground burrowing device according to claim 3 wherein:

(a) said inner cylinder means is connected to said outer casing with thefront and rear sections thereof spaced radially inwardly of said outercasing.

7. A two-way ground burrowing device according to claim 6 wherein:

(a) said rear anvil wall is disposed at the rearward end of said thirdchamber; and

(b) said third chamber is defined by the rear end of said ram, the rearanvil wall and the radial space between the rear section of said innercylinder means and said cylindrical duct.

8. A two-way ground burrowing device according to claim 7 wherein saidfirst valve means for selectively maintaining said third port meansopened or closed independently of the opening and closing thereof bysaid taining said third port means opened or closed independently of theopening and closing thereof by said ram comprises:

(a) a cylindrical slider member slidably received over the rear sectionof said inner cylinder means for movement between a first forwardposition sealingly overlying said third port means and a second rearwardposition spaced rearwardly of said third port means;

(b) a wall surface connected to said slider member and facing rearwardlyof said device;

(c) fourth port means for directing compressed air against said wallsurface to urge said slider member toward said first forward position;

(d) closure means positioned forwardly of said fourth port means;

(e) spring means for continuously exerting a predetermined force in therearward direction of said device to urge said slider member to saidsecond rearward position and said closure means against said fourth portmeans, said predetermined force being within the operating range of thepressure of the compressed air operating said device whereby compressedair supplied to said device at a pressure above said predeterminedpressure will move the closure means away from said fourth port meansand the slider member into said first forward position to operate thedevice with said third port means closed and compressed air supplied tosaid device at a pressure below said predetermined pressure will operatesaid device with said slider member in said second rearward positionspaced from said third port means.

10. A two-way ground burrowing device according to claim 7 wherein saidfirst valve means for selectively maintaining said third port meansopened or closed Independently of the opening and closing thereof bysaid ram comprises:

(a) a cylindrical slider member slidably received over the rear sectionof said inner cylinder means for movement between a first forwardposition sealingly overlying said third port means and a second rearwardposition spaced rearwardly of said third port means;

(b) a wall surface connected to said slider member and facing rearwardlyof said device; (c) fourth port means for directing compressed alragainst said wall surface to urge said slider member toward said firstforward position;

((1) spring means continuously exerting a predetermined force in therearward direction of said device to urge said slider member to saidsecond rearward position, said predetermined force being less than thepressure of the compressed air operating said device;

(e) a circumferentially extending ball race connected to said slidermember and facing radially inwardly of said device;

(f) a ball member disposed in said ball race;

(g) an axially extending concentrically located surface facing saidrace; and

(h) a guide track in said surface for supporting said ball member insaid ball race, said guide track having:

(1) a first branch section extending obliquely through a firstpredetermined distance toward the front of said device,

(2) a second branch section connected to said first 12 branch section ata point rearwardly of its forward end and extending obliquely toward therear of said device,

(3) a third branch section connected to said sec- 0nd branch section ata point forwardly of its rearward end and extending obliquely through asecond predetermined distance less than said first predetermineddistance toward the front of said device,

(4) a fourth branch section connected to said third branch section at apoint rearwardly of its forward end and extending obliquely toward therear of said device and connecting to another first branch section at apoint forwardly of its rearward end, said arrangement of said branchsections being repeated to form a continuous track around said surfacewhereby every other time compressed air is supplied to said device toact against said wall surface, said ball member will be caused to moveto the forward end of said first branch section to move said slidermember into said first position during operation of said device andevery alternate time compressed air is supplied to said device said ballmember will be caused to move to the forward end of said third branchsection to move said slider member into a third position located betweensaid first and second positions and spaced rearwardly of said third portmeans during operation of said device.

11. A two-way ground burrowing device comprising:

(a) an elongated outer casing having a tapered forward end and a hollowinterior;

(b) a ram disposed within the interior of said casing for axial movementtherealong;

(c) a front chamber disposed within the interior of said casing andcommunicating with the front end of said ram;

((1) a rear chamber disposed within the interior of said casing andcommunicating with the rear end of said ram;

(e) a front anvil wall positioned within the interior of said casing inthe path of forward movement of said ram;

(f) a rear anvil wall positioned within the interior of said casing inthe path of rearward movement of said ram;

(g) a compressed air inlet at the rear end of the interior of saidcasing adapted to be connected to an extraneous source of compressedair;

(h) conduit means for placing said front chamber in communication withsaid compressed air inlet for urging said ram in a rearward direction;

(i) primary port means for connecting the forward portion of said rearchamber to the exterior of said casing and adapted to be opened andclosed by said ram as it moves toward and away from said front anvilwall;

(j) auxiliary port means for connecting the rearward portion of saidrear chamber to the exterior of said casing and adapted to be closed andopened by said ram as it moves toward and away from said rear anvilwall;

(k) first valve means for selectively maintaining said auxiliary portmeans opened or closed independently of the opening and closing thereofby said ram; and

(l) second valve means for connecting and disconnecting said rearchamber to said source of compressed air.

12. A two-way ground burrowing device according to claim 11 wherein saidfirst valve means includes:

(a) a slider member slidably positioned within said casing for movementbetween a first forward position closing said auxiliary port means, asecond rearward position spaced rearwardly of said auxiliary 13 r portmeans and a thirdtforward positionv located between said first andsecond positions and spaced rearwardly of said auxiliary port means;

(b) control port 'me'anssfor directing compressed air against saidslider member to urgeit forwardly selectively toward said first forwardposition and said thirdforward position; i i

(c') means continuously exerting a predetermined force urging saidslider'm'e'mber' to said second rearward position, said predeterminedforce being less than the piessure of the compressed air operating saiddevice; and

(d) guiding means for controlling the axial movement of said slidermember between said first, second and third positions, said guidingmeans being constructed to successively locate said slider member insaid first and third positions each time said compressed air throughsaid control port means is discontinued and thereafter re-established.

13. A two-way ground burrowing device comprising:

(a) an elongated outer casing having a tapered for ward end and a hollowinterior;

(b) a ram disposed within the interior of said casing for axial movementtherealong, said ram having a front section of reduced cross-sectionaldimension and a rear section of enlarged cross-sectional dimension;

(c) first supporting means for slidably and sealingly supporting thefront section of said ram about its outer periphery;

(d) second supporting means for slidably and sealingly supporting therear section of said ram about its outer periphery;

(e) a first chamber disposed within the interior of said casing andcommunicating with the front end of said ram;

(f) a second chamber disposed within the interior of said casing andcommunicating with the intermediate portion of the piston where thefront and rear sections join each other, said second chamber beingisolated from said first chamber;

(g) a third chamber disposed within the interior of said casing andcommunicating with the rear end of said ram, said third chamber beingisolated from said second chamber and having one wall thereof defined bysaid second supporting means;

(h) a front anvil wall positioned within the interior of said casing inthe path of forward movement of said ram;

(i) a rear anvil wall positioned within the interior of said casing inthe path of rearward movement of said ram;

(j) a compressed air inlet at the rear end of the interior of saidcasing adapted to be connected to an extraneous source of compressedair;

(k) conduit means for continuously maintaining said first chamber incommunication with said compressed air inlet for continuously urgingsaid ram in a rearward direction;

(1) first port means for continuously maintaining said second chamber incommunication with the exterior of said casing;

(m) second port means in the second supporting means for connecting theforward end of said third chamber to the exterior of said casing, saidsecond port means being located immediately rearwardly of the rear endof said ram when said ram is in its forwardmost position abutting saidfront anvil wall and adapted to be closed from communication with saidthird chamber by the rear section of said ram when said ram is spacedrearwardly of said front anvil wall;

(n) third port means for connecting the rearward end of said rearchamber to the exterior of said casing, said third port means beinglocated in the second support means whereby it is closed by the rearsection of said ram immediately before said ram reaches its rearwardmostposition abutting said rear anvil wall;

(o),first valve means for-selectively maintaining said third port meansopened or closed. independently of the opening and closing thereof bysaid ram, said firstvalve means including;

(1) a slider member slidably positioned within said casing for movementbetween a first forward position sealing said' third port means, asecond rearward position spaced rearwardly of said third port means anda third forward position located between said first and second positionsand spaced rearwardly of said third port means;

(2) a wall surface connected to said slider member and facing rearwardlyof said device;

(3) fourth port means for directing compressed air against said wallsurface to urge said slider member forwardly selectively toward saidfirst forward position and said third forward position;

(4) spring means continuously exerting a predetermined force in therearward direction of said device to urge said slider member to saidsecond rearward position, said predetermined force being less than thepressure of the compressed air operating said device; and

(5) guiding means for controlling the axial movement of said slidermember between said first, second and third positions, said guidingmeans being constructed to successively locate said slider member insaid first and third positions each time said compressed air throughsaid fourth port means is discontinued and thereafter re-established;and

(p) second valve means for connecting and disconnecting said thirdchamber to said source of compressed air, said second valve means beingresponsive to changes in pressure in said third chamber and being openedby increased pressure in said third chamber.

14. A two-way ground burrowing device according to claim 13 wherein saidguiding means includes:

(a) a circumferentially extending ball race connected to said slidermember and facing radially inwardly of said device;

(b) a ball member disposed in said ball race;

(c) an axially extending concentrically located surface facing saidrace; and

(d) a guide track in said surface for supporting said ball member insaid ball race, said guide track having:

(1) a first branch section extending obliquely through a firstpredetermined distance toward the front of said device;

(2) a second branch section connected to said first branch section at apoint rearwardly of its forward end and extending obliquely toward therear of said device;

(3) a third branch section connected to said second branch section at apoint forwardly of its rearward end and extending obliquely through asecond predetermined distance less than said first predetermineddistance toward the front of said device; and

(4) a fourth branch section connected to said third branch section at apoint rearwardly of its forward end and extending obliquely toward therear of said device and connecting to another first branch section at apoint forwardly of its rearward end, said arrangement of said branchsections being repeated to form a continuous track around said surfacewhereby every other time compressed air is supplied to said device toact against said wall surface, said ball membet will be caused to moveto the forward end of said first branch section to move said slidermember into said first position during operation of said device andevery alternate time compressed air is supplied to said device said ballmember will be caused to move to the forward I end of said third branchsection to move said slider member into said third position located 1 6spaced rearwardly of said third port means during operation of saiddevice.

References Cited UNITED STATES PATENTS I 1/1919 Bull 173-9l 1,292,4292,312,367 3/1943 Gartin 91-236 3,137,483

6/ 1964 Zinkiewicz 173-91 between said first and second positions and 10JAMES A. LEPPINKlPrimary E xaminer.

